Add support to prevent overwriting existing files

[julianschiavo]

I noticed that if I re-saved a CreamAsset with the same object (so same object id) files could get duplicated. This avoids that by adding a property to the create/save methods.

This PR also adds support to create a CreamAsset with an object id (useful if you want to save an image for an id, but you haven't created the object yet)

[julianschiavo]

Hey @caiyue1993, any update on this? thanks!

[caiyue1993]

Hi @justjs , sorry for the delayed reply as the daily work is quite busy.
The changes looks good to me. But since lots of apps have been using IceCream, I have one concern. If a developer has modified binary value of an image related property(which is stored as CreamAsset) and our default overwriteExistingFile value is false, the newly updated image will not be saved. Right?

[julianschiavo]

Fair enough. I made these changes to try and fix the realm database getting tons of duplicate CreamAsset ids, and this seems to fix it for me. Is these a better way?

[caiyue1993]

I've retested the different cases and changed the default shouldOverwrite value from false to true. We really need to consider the compatibility.

If the default shouldOverwrite is false, the newly updated asset will not be saved. So that's unacceptable for the already-used developers. You could have a try on the example project:

IceCream/Example/IceCream_Example/DogsViewController.swift

Line 111 in cac9d2a

dog.avatar = CreamAsset.create(object: dog, propName: Dog.AVATAR_KEY, data: imageData)

After my tweaks, you need to explicitly set the shouldOverwrite value to false where using CreamAsset if you don't want to update the existing file.

This pr is gonna ready to be merged. Thanks again @justjs !

[julianschiavo]

Fair enough, that makes sense. Happy to hear we can merge this 🙂